Method and system for optimizing and preventing failure of sender policy framework (SPF) lookups

ABSTRACT

The present invention circumvents the standard SPF lookup limit by allowing an administrator to create a secondary SPF record that includes all the desired SPF records even if it exceeds the 10 recursive lookups that would result in a standard failure. The administrator would then then create or modify their main SPF record to include an entry that points to the SPF Proxy that is the subject of this invention.

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority from U.S. Provisional Patent Application Ser. No. 62/232,566, entitled “Method and System for Optimizing and Preventing Failure of Sender Policy Framework (SPF) Lookups”, filed on Sep. 25, 2015.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to email applications. More specifically, the present invention relates to overcoming current limitations which commonly cause Sender Policy Framework (SPF) email authentication problems for legitimate senders.

BACKGROUND OF THE INVENTION

Sender Policy Framework (SPF) is a system implemented by most email service providers that helps to reduce Electronic Mail (email) “spam” that is forged by a malicious system or entity. At a high level, SPF allows an administrator for a DNS domain (eg: example.com) to authorize a set of servers to send email on behalf of the domain. The authorization is most commonly based on the Internet Protocol (IP) address of the server that is sending the email.

As more companies outsource email related functionality to 3rd party providers, it is important for the administrators for these companies to authorize the 3rd parties to send email on their behalf. For example, a company may want a bulk mail service provider such as MAILCHIMP to send email on the company's behalf. To do this, the company will “include” an SPF record from MAILCHIMP or any other service provider they use.

Each included record is recursively searched for more records until they all are resolved to specific IP address ranges. This recursive lookup can cause problems, and is the subject of the invention presented in this patent filing. The SPF RFCs define a hard limit of 10 recursive lookups, after which, an SPF check will fail. A failed SPF check can have a detrimental effect on deliverability of email and cause messages to be outright rejected or placed into a junk mail folder.

Definitions

Unless stated to the contrary, for the purposes of the present disclosure, the following terms shall have the following definitions:

“Application software” is a set of one or more programs designed to carry out operations for a specific application. Application software cannot run on itself but is dependent on system software to execute. Examples of application software include MS Word, MS Excel, a console game, a library management system, a spreadsheet system etc. The term is used to distinguish such software from another type of computer program referred to as system software, which manages and integrates a computer's capabilities but does not directly perform tasks that benefit the user. The system software serves the application, which in turn serves the user.

The term “app” is a shortening of the term “application software”. It has become very popular and in 2010 was listed as “Word of the Year” by the American Dialect Society

“Apps” are usually available through application distribution platforms, which began appearing in 2008 and are typically operated by the owner of the mobile operating system. Some apps are free, while others must be bought. Usually, they are downloaded from the platform to a target device, but sometimes they can be downloaded to laptops or desktop computers.

“API” In computer programming, an application programming interface (API) is a set of routines, protocols, and tools for building software applications. An API expresses a software component in terms of its operations, inputs, outputs, and underlying types. An API defines functionalities that are independent of their respective implementations, which allows definitions and implementations to vary without compromising each other.

The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates domain names, which can be easily memorized by humans, to the numerical IP addresses needed for the purpose of computer services and devices worldwide. The Domain Name System is an essential component of the functionality of most Internet services because it is the Internet's primary directory service.

“Email” or “electronic messages” is defined as a means or system for transmitting messages electronically as between computers or mobile electronic devices on a network.

“Email Client” or more formally mail user agent (MUA) is a computer program used to access and manage a user's email. A web application that provides message management, composition, and reception functions is sometimes also considered an email client, but more commonly referred to as webmail.

“GUI”. In computing, a graphical user interface (GUI) sometimes pronounced “gooey” (or “gee-you-eye”)) is a type of interface that allows users to interact with electronic devices through graphical icons and visual indicators such as secondary notation, as opposed to text-based interfaces, typed command labels or text navigation. GUIs were introduced in reaction to the perceived steep learning curve of command-line interfaces (CLIs), which require commands to be typed on the keyboard.

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems.[1] HTTP is the foundation of data communication for the World Wide Web. Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text. HTTP is the protocol to exchange or transfer hypertext.

The Internet Protocol (IP) is the principal communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.

An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing.

An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet.

A “mobile app” is a computer program designed to run on smartphones, tablet computers and other mobile devices, which the Applicant/Inventor refers to generically as “a computing device”, which is not intended to be all inclusive of all computers and mobile devices that are capable of executing software applications.

A “mobile device” is a generic term used to refer to a variety of devices that allow people to access data and information from where ever they are. This includes cell phones and other portable devices such as, but not limited to, PDAs, Pads, smartphones, and laptop computers.

A “module” in software is a part of a program. Programs are composed of one or more independently developed modules that are not combined until the program is linked. A single module can contain one or several routines or steps.

A “module” in hardware, is a self-contained component.\

Resource records (RRs) are the data records permissible in zone files of the Domain Name System (DNS).

Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (email) transmission.

“SMTP Relay”, which stands for Simple Mail Transfer Protocol, lets you send email messages through your email account using your existing email service.

“SPF” is the abbreviation for Sender Policy Framework. “SPF record”. For the purposes of this document, an SPF record refers to either a standard DNS TXT resource record or SPF resource record.

A “software application” is a program or group of programs designed for end users. Application software can be divided into two general classes: systems software and applications software. Systems software consists of low-level programs that interact with the computer at a very basic level. This includes operating systems, compilers, and utilities for managing computer resources. In contrast, applications software (also called end-user programs) includes database programs, word processors, and spreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities.

A “software module” is a file that contains instructions. “Module” implies a single executable file that is only a part of the application, such as a DLL. When referring to an entire program, the terms “application” and “software program” are typically used. A software module is defined as a series of process steps stored in an electronic memory of an electronic device and executed by the processor of an electronic device such as a computer, pad, smart phone, or other equivalent device known in the prior art.

A “software application module” is a program or group of programs designed for end users that contains one or more files that contains instructions to be executed by a computer or other equivalent device.

Spam or SPAM commonly refers to: Spamming, unsolicited or undesired electronic messages; Email spam, unsolicited, undesired, or illegal email messages; spam messages, unsolicited, undesired, or illegal messages in general (private messages on websites, sms, messenger etc.

A “computer system” or “system” consists of hardware components that have been carefully chosen so that they work well together and software components or programs that run in the computer. The main software component is itself an operating system that manages and provides services to other programs that can be run in the computer. The complete computer made up of the CPU, memory and related electronics (main cabinet), all the peripheral devices connected to it and its operating system. Computer systems fall into two categories: clients and servers.

URL is an abbreviation of Uniform Resource Locator (URL), it is the global address of documents and other resources on the World Wide Web (also referred to as the “Internet”).

A “User” is any person registered to use the computer system executing the method of the present invention.

In computing, a “user agent” or “useragent” is software (a software agent) that is acting on behalf of a user. For example, an email reader is a mail user agent, and in the Session Initiation Protocol (SIP), the term user agent refers to both end points of a communications session. In many cases, a user agent acts as a client in a network protocol used in communications within a client—server distributed computing system. In particular, the Hypertext Transfer Protocol (HTTP) identifies the client software originating the request, using a “User-Agent” header, even when the client is not operated by a user. The SIP protocol (based on HTTP) followed this usage.

A “web application” or “web app” is any application software that runs in a web browser and is created in a browser-supported programming language (such as the combination of JavaScript, HTML and CSS) and relies on a web browser to render the application.

A “website”, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet address known as a Uniform Resource Locator (URL). All publicly accessible websites collectively constitute the World Wide Web.

A “web page”, also written as webpage is a document, typically written in plain text interspersed with formatting instructions of Hypertext Markup Language (HTML, XHTML). A web page may incorporate elements from other websites with suitable markup anchors.

Web pages are accessed and transported with the Hypertext Transfer Protocol (HTTP), which may optionally employ encryption (HTTP Secure, HTTPS) to provide security and privacy for the user of the web page content. The user's application, often a web browser displayed on a computer, renders the page content according to its HTML markup instructions onto a display terminal. The pages of a website can usually be accessed from a simple Uniform Resource Locator (URL) called the homepage. The URLs of the pages organize them into a hierarchy, although hyperlinking between them conveys the reader's perceived site structure and guides the reader's navigation of the site.

SUMMARY OF THE INVENTION

The present invention circumvents the standard SPF lookup limit by allowing an administrator to create a secondary SPF record that includes all the desired SPF records even if it exceeds the 10 recursive lookups that would result in a standard failure. The administrator would then then create or modify their main SPF record to include an entry that points to the SPF Proxy that is the subject of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

FIG. 1 is a flow chart illustrating the process/method for optimizing and preventing failure of sender policy framework (SPF) lookups.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description of the invention of exemplary embodiments of the invention, reference is made to the accompanying drawings (where like numbers represent like elements), which form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, but other embodiments may be utilized and logical, mechanical, electrical, and other changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it is understood that the invention may be practiced without these specific details. In other instances, well-known structures and techniques known to one of ordinary skill in the art have not been shown in detail in order not to obscure the invention. Referring to the FIGURES, it is possible to see the various major elements constituting the present invention.

Sender Policy Framework (SPF) is a system implemented by most email service providers that helps to reduce Electronic Mail (email) “spam” that is forged by a malicious system or entity. At a high level, SPF allows an administrator for a DNS domain (eg: example.com) to authorize a set of servers to send email on behalf of the domain. The authorization is most commonly based on the Internet Protocol (IP) address of the server that is sending the email.

As more companies outsource email related functionality to 3rd party providers, it is important for the administrators for these companies to authorize the 3rd parties to send email on their behalf. For example, a company may want a bulk mail service provider such as MAILCHIMP to send email on the company's behalf. To do this, the company will “include” an SPF record from MAILCHIMP or any other service provider they use. For example, the following record will authorized GOOGLE and MAILCHIMP to send email on behalf of example.com.

-   example.com 60 IN TXT “v=spfl include:_spf.google.com     include:spf.mailchimp.com˜all”3

Each included record is recursively searched for more records until they all are resolved to specific IP address ranges. This recursive lookup can cause problems, and is the subject of the invention presented in this patent filing. The SPF RFCs define a hard limit of 10 recursive lookups, after which, an SPF check will fail. A failed SPF check can have a detrimental effect on deliverability of email and cause messages to be outright rejected or placed into a junk mail folder.

The invention presented here circumvents the lookup limit by allowing the administrator of example.com to create a secondary SPF record such as spfproxy.example.com that includes all the desired SPF records even if it exceeds the 10 recursive lookups. The administrator would then then create or modify their main SPF record for example.com to include an entry that points the SPF Proxy that is the subject of this invention.

Now referring to FIG. 1, in step 1 an email is sent from a mail server 101 that purports to be from adam@example.com to eve@acme.com. The email can be sent from adam@example.com's corporate email servers or from a variety of 3rd party email providers. The email has the following example properties that will be used for SPF Macros: IP: 1.1.1.1; Version: in-addr; EHLO/HELO: mail.google.com; Local Part: adam; and Domain Part: example.com.

In step 2, acme.com's email server 102 attempts to do an SPF validation using example.com's SPF record. Acme.com's email server 102 does a DNS request for TXT example.com.

In step 3, example.com's DNS service 103 responds with an SPF Proxy Record: eg: “v=spfl include: %{l}._1.%{i}._i.%{v}._v.%{h}._h.%{d}._d.spfproxy.org˜all”

In step 4, example.com's DNS server 103 is processing the Macro's in the returned Proxy Record and makes a DNS TXT request to spfproxy.org: adam._1.1.1.1.1._i.in-addr._v.mail.google.com._h.example.com._d.spfproxy.org

In step 5, spfproxy.org 104 receives the request and extracts the merged macro's. spfproxy.org 104 looks up the Canonical SPF Record from example.com's DNS server 103 by making a request for _spfproxy.example.com, eg: “v=spfl include:_spf.google.com include:spf.mailchimp.com˜all”. The canonical record can be determined by an optional or required “selector” contained within the Proxy Record. This will allow the SPF Proxy service to use <selector>.example.com instead of hardcoding_spfproxy.example.com.

In step 6, spfproxy.org 104 now does a standard SPF validation, with the exception of now removing the 10 Lookup limit that is imposed by the SPF RFC.

In step 7, spfproxy.org 104 constructs a Synthetic response record based on the results from step 6 which acme.com can use to do a simple check. The synthetic record can for example contain a single block of IPs, or a single include SPF entry. It can also return an “exists” entry or “redirect” entry.

All DNS entries, IP address, hostnames, and DNS Macro's are listed here for example purposes only and can vary in implementation scenarios.

The system is set to run on a computing device or mobile electronic device. A computing device or mobile electronic device on which the present invention can run would be comprised of a CPU, Hard Disk Drive, Keyboard, Monitor, CPU Main Memory and a portion of main memory where the system resides and executes. Any general-purpose computer, smartphone, or other mobile electronic device with an appropriate amount of storage space is suitable for this purpose. Computer and mobile electronic devices like these are well known in the art and are not pertinent to the invention. The system can also be written in a number of different languages and run on a number of different operating systems and platforms.

Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the point and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

As to a further discussion of the manner of usage and operation of the present invention, the same should be apparent from the above description. Accordingly, no further discussion relating to the manner of usage and operation will be provided.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. 

The invention claimed is:
 1. A method for optimizing and preventing failure of sender policy framework (SPF) lookups recorded on non-transitory computer-readable medium and capable of execution by a computer, the method comprising the steps of: requesting a regular SPF Record; receiving a SPF Record that points to a Proxy Server (SPF Proxy Record); conditionally checking a Proxy DNS entry based on merged SPF Macros; performing an SPF authentication check based on a conditionally received DNS record; and returning a Synthetic SPF response that incorporates the results of the SPF authentication check in a format that adheres to the SPF standard and whose result would match the SPF authentication check result even without DNS lookup limits; responding with the same Synthetic SPF response regardless of EHLO or IP information; the Synthetic SPF response contains a single block of IPs or a single included SPF entry; the Synthetic SPF response contains a single included SPF “exists” entry or “redirect” entry; the Synthetic SPF response is the same across all requests; and the Synthetic SPF response includes a chain of include entries if the synthetic record exceeds the size of a record based on the SPF protocol specification.
 2. The method of claim 1, further comprising the step of: changing the required behavior of the SPF authentication check by increasing a DNS lookup limit; not varying the Synthetic SPF response; and returning a flattened list of authorized networks.
 3. The method of claim 1, further comprising the step of: using a cached response from a previous lookup that matches completely.
 4. A method for optimizing and preventing failure of sender policy framework (SPF) lookups recorded on non-transitory computer-readable medium and capable of execution by a computer, the method comprising the steps of: sending an email from a mail server; the email contains one or more properties that will be used for one or more SPF Macros; attempting to do an SPF validation using email domain's SPF record; making a DNS request; responding with an SPF Proxy Record; processing the SPF Macros in a returned Proxy Record; generating a DNS TXT request to the domain's SPF proxy; receiving the DNS TXT request and extracts a merged macro; looking up a Canonical SPF Record from the email domain's DNS server by making a request; conducting a standard SPF validation; and constructing a synthetic response record based on the results from the standard SPF validation; responding with the same constructed synthetic response record regardless of EHLO or IP information; the synthetic response record contains a single block of IPs or a single included SPF entry; the synthetic response record contains a single included SPF “exists” entry or “redirect” entry; the synthetic response record is the same across all requests; and the synthetic response record includes a chain of include entries if the synthetic response record exceeds the size of a record based on the SPF protocol specification.
 5. The method of claim 4, wherein the email is from an actual mail server for the domain or a third party email provider.
 6. The method of claim 4, wherein the Canonical SPF record is determined by an optional or required “selector” contained within the proxy record; and the email domain's SPF records are static. 